Optical smoke detector



y 15, 1952 c. N. CAHUSAC ETAL OPTICAL SMOKE DETECTOR 3 Sheets-Sheet 1Filed NOV. 14, 1949 INVENTORS CZ ARE/VCE/VOEL CAA/UJAC ANo FEAN/(B-/4LLEN BY M V ATTOR/Vf-X July 15, 1952 c. N. CAHUSAC ET AL OPTICAL SMOKEDETECTOR 5 Sheets-Sheet 2 Filed N03. 14, 1949 INVENTORS a/wz/vcz/voaCAI/6454C BYA/VD FRANK 5. A4 4 EN ATTORNEX y 15, 9 c. N. CAHUS'AC ETAL2,603,122

OPTICAL SMOKE DETECTOR Filed Nov. 14, 1949 5 Sheets-Sheet 3 IN VEN TORSC1. AREA/CE N054 CAI-IUSAC zwo Few/w 5. ,44 2 EN WWW Patented July 15,1952 2,603,122 OPTICAL SMOKE DETECTOR Clarence Noel Cahusac, Newark, andFrank B.

Allen, Towaco, N. J assignors to C-O-Two Fire Equipment Company, Newark,N. J a corporation of Delaware Application November 14, 1949, Serial No.126,966 1 Claim. (01. 8814) This invention relates to smoke detectorsand, more particularly, to a smoke detector for use on a vehicle such asan airplane in which the detector preferably is mounted on theinstrument panel.

Heretofore, visual smoke detectors have been provided for shipboardinstallation. However, such apparatus have been large and cumbersome andunsuited for use in vehicles such as an airplane in which space andweight is limited. Smoke detectors have also been provided of theaudible type in which an alarm is given when smoke varies the light on aphotoelectric element initiating an alarm. While generally satisfactory,it is possible for the audible smoke detector to become defective andcause an alarm signal to be given when in fact no smoke is present. Inthis case serious harm might be done if a fire extinguishing agent wereto be discharged into the engines or other parts of the plane.

The present invention aims to overcome the foregoing difficulties anddisadvantages by providing a visual smoke detector which is light inweight and compact in size.

Another object of the invention is to provide.

a smoke detector which is simple and economical in manufacture,efiicient in operation and durable in use.

In accordance with the invention a smoke detector is provided which maybe mounted on the instrument panelof the vehicle such as an airplane.Air to be tested for smoke is caused to fiow through the detector into abeam of light. In the event smoke is present in the air the smokeparticles reflect light into the range of sight of the pilot therebyattracting attention and also providing a positive check indication ofsmoke in the event an alarm signal has been given by an audible smokedetector. The detector casing is so constructed that the beam of lightnormally is not visible from the viewing opening of the detector, thelight being-visible only when reflected from the particles of smoke.

A smoke detector in accordance with the invention is advantageous notonly in detecting smoke but also for indicating the absence of smokeafter the fire has been extinguished.

Other objects and advantages of the invention will be apparent from thefollowing description and from the accompanying drawings which show, byway of example. embodiments of the invention.

In the drawings:

Figure 1 is a front view of a smoke detector constructed in accordancewith the invention.

Figure 2 is a rear view of the smoke detector.

Figure 3 is a plan view of the smoke detector with its top coverremoved.

Figure 4 is a vertical longitudinal sectional view of the smoke detectortaken along the line 4-4 of Figure .3.

Figure 5 is a vertical longitudinal sectional 2 view of the smokedetector taken along the line 5--5 of Figure 3.

Figure 6 is a vertical transverse sectional view of the smoke detectortaken along the line 6-6 of Figure 4.

Figure 7 is a sectional view corresponding to Figure 4 of anotherembodiment of the smoke detector in accordance with the invention.

Figure 8 is a plan view ofthe smoke detector shown in Figure 7.

Figure 9 is a front view of the smoke detector shown in Figure '7. 7

Referring to the drawings there is shown a smoke detector l inaccordance with the invention. In the embodiment shown in the drawingsthe smoke detector is made with two testing compartments 2, each adaptedto be connected by piping (not shown) to one or more compartments of avehicle or other space of a structure to be supervised for the presenceof smoke. Suitable means such as a suction pump may be used to circulateair from the compartment through the smoke detector and may be connectedin the piping at any desired location. The smoke detector I includes ahousing 4 enclosing a pair of light sources 6 each adapted to project abeam of light through a lens 8 into one of the smoke detectingcompartments 2. Viewing windows I0 are provided for each of the smokedetecting compartments 2.

The housing 4 may be made of any suitable material, preferably light inweight, and may be molded or cast if desired. Space is provided in thehousing 4 for the pair of testing compartments 2 positioned side by sideand separated by a partition ll. Another partition l2 separates thetesting compartments 2 from a space M for the light sources 6. Stillanother partition 16 abutting against the partition l2 provides a spaceor compartment I8 for electrical connection means. An inlet passage foreach of the smoke testing compartments 2 is made by forming a passage 22through a thickened portion of the housing 4 and entering the smokedetecting compartment 2 as indicated at 24. An outlet for the testingcompartments 2 is provided at 26 into a passage 28 extending through thepartition l2 in fluid communication. with a second passage 30 throughthe partition l6 and through a third passage 32 in a thickened portionof the bottom of the housing 4. In an equivalent construction the outletpassage might be positioned in the lower edge of the partition l2adjacent to the bottom of the casing or in a thickened portion of thebottom of the easing. Usual connection fittings 34 are provided toconnect piping to the smoke detector housing.

The light source 6 is preferably an electric bulb carried in a socket 38with terminals 40 connected by wires 42 to a disconnecting socket 44secured in position in an opening in the housing 4 in any suitablemanner such as. by screws 46 extending through openings in the housinginto threaded apertures in the disconnecting sockets.

The lens 8 is mounted in an opening in the partition I2 and secured inposition by the lens retaining member 48 threadedly engaged with thewall of the opening.

The viewing members III are positioned on the front of the smokedetector. Frames 50 of the windows I each have an annular shoulder 52against which is positioned the viewing window transparent material 54made of glass or plastic, cushioned by gaskets 56 and held in positionby the ring nut 58 threadedly engaged with the inner surface of theframe. Baffle members 60 and 62 are each secured to the partition I I asby screws 64 and have openings 66 and, 68 therein providing an angle ofsight view across the path of a beam of light projected from thelightbulb 6 through the lens 8 into the detecting compartment 2. Anyequivalent baflle means may be provided, such as the use of stripsextending inwardly from the wall of the casing and arranged to providethe viewing openings or apertured baille means.

The openings 66 and 68 in the bailie members 60 and 62 are so arrangedas to prevent extraneous rays of light from the light compartment fromescaping into the range of sight of the operator of the vehicle in orderto prevent eye strain and loss of night vision. In order to absorbextraneous rays of light within the detecting compartments 2 the innersurfaces thereof are covered with a light absorbing material such ascarpet pile 10, a spot being burned in the pile of the fabric asindicated at 12 to provide a pocket at the focal point of the rays oflight projected by the lens 8. The smoke detector housing 4 is closed onits top, bottom, and side walls, and on its rear by thin cover plates I4secured in position by screws or the like 16 extending through aperturesin the cover plates to engage in screw holes in the body of the housing4.

The front end of the housing is closed by a decorative cover plate 11having an aperture approximately in the center thereof to receive a lug18 extending from the housing 4 and engaged by a conventional slidefastener 80. The outer end of the lug I8 is made with an annular groovetherein for engagement by the slide fastener to provide for the quickand easy removal of the cover plate for an inspection of the interior ofthe smoke detector or to replace the electric bulbs 6. The cover plateI! is apertured to provide a view through the windows I0 in alignmentwith the openings 66 and 68 of the bafiie members 60 and 82.

In order that a visual indication may be had as to the operability ofthe electric bulbs 6, sight openings are provided in the cover plate I'Ias indicated at 82 and each are backed by a small piece ofsemi-transparent material B4to permit the passage of only a small amountof light from the lamp bulb.

In Figures 7 through 9 another embodiment of the invention isillustrated in which corresponding parts are designated by the samereference numbers as in Figures 1 through 6 with the addition of I00.The smoke detector IOI differs principally from the smoke detector I inhaving a transparent window or plate I86, covering substantially thefront face of the detector, and in this form of the invention thepartition I I2 at its front end I88 is turned upwardly to abut againstthe top corner of the casing. A passage I90 is formed in the partitionI88 for light to pass through the semi-transparent material I84 toindicate the operability of the lamp bulb I06. In the embodiment shownthe window I86 is spaced as indicated at I90 from the front wall I9I ofthe detecting compartment I02. If preferred, a barrier might b placed inthe space I90 between the front wall I9I of the detecting compartmentand the window I86 to entirely isolate each compartment from the other.However, it has been found unnecessary to use such a partition orbarrier as the smoke which may be present in either of the detectingcompartments is evacuated through the outlet I26 without entering thespace. This embodiment of the invention is advantageous in that a smokedetector is provided having a transparent face adapted to conform insize and appearance to the other instruments on the panel. 4

While the invention has been described and illustrated with reference tospecific embodiments thereof, it will be understood that otherembodiments may be resorted to or changes made therein without departingfrom the invention. Therefore, the form of the invention set out aboveshould be considered as illustrative and not as limiting the scope ofthe following claim.

We claim:

A smoke detector for use on the instrument board of a vehicle, thedetector comprising a casing of elongated shape and adapted to fit oneof the usual instrument openings on the control board, a longitudinallyextending partition for the front portion of the casing defining a lightsource compartment and a detecting compartment positioned side-by-side,a light source in the light compartment, lens means in the partition toproject a beam of light into the detecting compartment, a transverselyextending partition abutting the longitudinally extending partition andproviding the rear end walls for the light and detecting compartmentsand defining a front wall for a wire connection compartment positionedin the rear of said light and detecting compartments for connection ofwires between the lamp and the rear wall of the casing, means providingan inlet and an outlet for fluid to be tested for smoke terminating onthe rear Wall of the casing, said inlet means providing fluidcommunication to the detecting compartment, transparent viewing meansproviding a front wall for the detecting compartment, apertured bafllemeans between the transparent wall and the detecting compartment torestrict the angle of view approximately transversely of the beam oflight, and means providing a passageway in the transversely andlongitudinally extending partition walls to lead the smoke from thedetecting compartment to the outlet on the rear wall, whereby theconnecting fittings for the fluid inlet and outlet and for theelectrical connections are accessible on the rear Wall of the casing.

CLARENCE NOEL CAI-IUSAC.

FRANK B. ALLEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,042,095 Grant May 26, 19352,299,457 Cahusac et al. Oct. 10, 1942 FOREIGN PATENTS Number CountryDate 447,820 Great Britain May 26, 1936

